Combined Scale Factor Helper
Combines grid and elevation scale factors to convert between ground and grid distances.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the grid (point) scale factor.
- Enter the ground height above the ellipsoid.
- Press Calculate for the combined scale factor.
How it works
Combined scale factor = grid scale factor × elevation factor, where the elevation factor = R ÷ (R + height). Multiply a ground distance by this to get the grid distance.
Worked example
Grid 0.99960, height 400 m. Elevation factor ≈ 0.99994, combined ≈ 0.99954.
Frequently asked questions
Ground to grid or grid to ground?
Multiply ground distance by the combined scale factor to get grid distance; divide to go the other way.
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Cite this tool
Zerdly. (2026). Combined Scale Factor Helper. Retrieved from https://www.zerdly.com/tools/combined-scale-factor-helper/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.